Presentation
An 80 year-old male patient presenting with vertigo.
Patient Data
Color Doppler Ultrasonography of the vertebral arteries shows a complete reversal of blood flow on the left side. The left vertebral artery shows blue due to retrograde flow. The right vertebral artery shows normal antegrade flow shown as red in color.
Bilateral carotid arteries show normal antegrade flow also shown in red color.
The left brachial artery shows a monophasic while the right brachial artery shows a triphasic waveform.
All these findings imply an occlusion or high-grade stenosis of the left proximal subclavian artery.
Occlusion of the left subclavian artery at its origin measuring approximately 2 cm in length. Blood is drawn from the vertebral artery to provide flow in the affected subclavian artery distal to the stenosis.
Occlusion of the left subclavian artery (yellow arrow) at its origin measuring approximately 2 cm in length.
Blood is drawn from the vertebral artery (red arrow) to provide flow in the affected subclavian artery distal to the stenosis.
Case Discussion
Subclavian steal phenomenon results from occlusion or severe stenosis of the proximal subclavian artery resulting in retrograde flow in the ipsilateral vertebral artery and mono-biphasic flow pattern in the ipsilateral arm arteries (decreased blood pressure in the ipsilateral brachial artery compared to contralateral side).
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